Coupling between radio apparatus and high-tension transmission line



Aug. 21, 1928.

P. TATZ COUPLING BETWEEN RADIO APPARATUS AND HIGH TENSION TRANSMISSION LINE Filed Dec. s, 1924 APPARATUS ABSORPTION RESISTANCE TRANSM/SS/ON l/NE .CARR/ER C/lO/(f COUPU/VG W/Af L RECf/VER POWER APPARATUS ABSORPTION RES/STANCE TRANSMISSION 1/:

' I CARR/ER -CHOKE COUPU/V6 WIRE POWER ABSURPf/O/V APPARATUS mum/rm RPS/STANCE 2 mA/sM/ss/zm l/A/E INVENTOR PAUL TATZ ORNEY Patented Aug. 21, 1928.

UNITED STATES PATENT OFFICE.

PAUL TATZ, OF BERLIN, GERMANY, ASSIGNOR TO GESELLSCHAFT Ffi'R DRAHTLOSE TELEGRAI'HIE M. 13. IL, 0]? BERLIN, GERMANY, A CORPORATION OF GERMANY.

COUPLING BETWEEN RADIO APPARATUS AND HIGH-TENSION TRANSMISSION LINE.

Application filed December 8, 1924, Serial No.

My invention relates generally to the art of using radio frequency signalling current on existing high tension power transmission lines and more specifically to means for coupling the signalling apparatus to the transmission line.

It has for its object to provide a coupling between the radio signalling apparatus and the transmission line which will ofier mini mum impedance to signalling currents and yet will not interfere with the operation of the transmission line from. a power stand point.

Other objects will be apparent from the following specification and claims considered in connection withthe drawings in which;

Figure 1 represents an embodiment of iny invention,

Figure 2 represents another form of my invention,

Figure 3 represents a modified form of my invention.

Int-he use of carrier frequency telephony are different in their principles, were em ployed. The simplest arrangement was obtained by connecting the radio frequency apparatus across high tension condensers directly to the transmission lines, this expedient taking advanta e of the considerable difference in impedance of the condensers with regardto high frequency and low frequency.

In order to avoid special coupling condensers, one soon came upon the idea of employing the normal arrangements of high tension buildings for this purpose by insulating the suitable apparatus from earth and utilizing their capacities with regard to earth for coupling purposes and by using the earth as return conductor. This method was, for instance, employed using the high tension wall bushings or ducts. As the disturbing capacity with regard to earth could not be eliminated in practice, this method has been almost abandoned.

For transmission lines of low and medium 754,480, and in Germany December 18, 1923'.

voltage the coupling by means of condensers could always be successfully used, as the high tension condensers had relatively large capacities, in comparison with which the disturbing capacity of the arrangements of the high tension buildings was of no great importance. 1

The conditions are different for very high voltages. One tried to overcome the difficulties by using aerials which were arranged in parallel to the transmission lines and fastened on the same or special masts. n Also in this case one soon came upon the idea of utilizing the already existing arrangements of the transmission lines, as, for instance, lightning-conductor cables, for this purpose.

Itwas now found in practice that nothing could be attained by a'short aerial; it was necessary to use'aerials of more than 500 meters in length, that is, lengths which corv respond to that wavelength which is usually employed for the carrier frequency. These carrier frequencies may not, as known, betoo low in order to avoid difiiculties, for instance, in the solution of the problem of bridging over disconnecting switches.

The last mentioned fact caused new difficulties. If the relation of the transmission of radio frequency upon the frequency is tested by means of a certain aerial arrangement at both ends of the transmission line, distinct maxima and minima are found which could not be explained by the different qualities. that is, natural frequencies of the transmission line. It is impossible that the characteristic curve of the transmission line could show such great differences.

It was, for instance, found that one coupling wire oscillating on one wavelength is not adapted for transfer of energy. Practice shows plainly that there are certain favorable carrier frequencies particularly due to the qualities of the coupling wires and not to those of the transmission line. Consequently ing the reflection of the Waves by absorbing ent invention, which is based upon the fact that the generation of stationary oscillations is prevented in a known manner by suppressthem by. suitable resistances. In. case of horizontal linear systems, of conductors, the

result is attained that the waves can be transferred to and propagated over the transmission lines, and radiated. 'Theadvantages of this method are very clear; independence of the frequency and unlimited adaptation of the length of the coupling wires to the energy relations, and so on.

The practical embodiment of the invention is carried out in the following Way. It is appropriate to use separate coupling wires for'transmission and reception. Lightning conductor cables which are insulated for a certain distance, are appropriately employed ceiver itself, an impedance can, be connected in parallel to the tuning means of the aerial of the receiver; this impedance is'so dimen sioned that it is very high for the receiving frequency but almost equal to .zero for the transmitting frequency. The coupling wire of the transmitter is connected to earth across the absorption resistance at a suitable distance from the high tension building as shown in Fig. 2.

In 'order to eliminate the disturbing 111-,

fluence of stationary oscillations on the propagation of the Waves over the transmission lines, suitable absorption resistances R can be connected across high tension condensers S to the ends of the lines one end of the'line being shown in Fig. 3. The capacity of the high tension transmission-line with regard to the carrier frequencies may be compensated by a series connected inductance. The re sistances of the high tension condensers and inductanccs which cause losses must be taken into consideration with regard to the dimensioning of the absorption resistance. It is also possible to avoid a special absorption resistance by suitably dimensioning the loss resistances. In all cases in which the arrangements of the high tension building represent a high capacitive shunt, the transmission lines canbe choked from the transmisison line switches, whereby at the same time a dis-.

turbance of the conditions is avoided when the transmission line is earthed in the high tension building.

It is obvious that corresponding measures can be taken in case of pure coupling by means of condensers in order to avoid the production of stationary oscillations.

Having described my invention, I claim:

1. The method of transferring radio frequency signals to and from-ahigh tension transmission system which comprises transferring the radio frequency signalto or from the high tension. line by capacitive coupling and preventing the development of stationary oscillations in said coupling by absorbmg the'progressive' oscillations in resistance elements.

mission line with a radio frequency signaling system comprising a high tension line, a coupling line, a radio frequency circuit and a resistance element in said coupling line adapted to absorb progressive oscillations in said coupling line.

3. The combination in a radio frequency telephony system of a high tension transmission line and a radio frequencytelephony circuit, means for coupling said circuit to the line including resistancecelements adapted to absorb progressive oscillations in said coupling means.

4. The combination in a radio frequency telephony system of a high tension transmis; sion line and a radio frequency telephony circuit, means for coupling said circuit to said line, said ineans including a resistance element and a high frequency condenser .con-

so 2. The combination of a high tension trans nccted to the end of said coupling means, said resistance being adapted to absorb the pro gressive oscillations in said coupling means. 1 5. In combination, a high tension power line, aradio frequency receiving system and means for coupling said system with saidpower line, said means comprising an antenna, means for tuning said antenna and means connected to said antenna for absorbing progressive oscillations therein.

6. In combination, a high tension power line, means for impressing signal currents of a given frequency on said line, a high frequency receiving system tuned to a different frequency and means for coupling said system with said power line and including an antenna, a resistance element connected to said antenna for absorbing stationary oscillations therein and means connected to said antenna whereby said receiving system is .renderednon-responsive to said first mentioned signal currents.

' PAUL TATZ. 

